Horticultural luminaire, horticultural lighting arrangement and method for controlling horticultural lighting arrangement

ABSTRACT

A horticultural luminaire, a horticultural lighting arrangement including a plurality of the horticultural luminaires, and a method for controlling the horticultural lighting arrangement are described. The horticultural luminaire includes a main light emitting unit including at least one LED for generating a main spectrum, an environmental sensor for measuring environmental data, and control electronics for determining a position data representing position of the horticultural luminaire, sending out the environmental data and the position data, receiving control data, and controlling the emission intensity of the main light emitting unit on the basis of the control data.

FIELD OF THE INVENTION

The present disclosure relates to lighting arrangements, and particularly to controlling lighting in horticultural lighting arrangements.

BACKGROUND OF THE INVENTION

Green houses and growth rooms utilize artificial lighting in supplementing, supporting or replacing natural light provided by the sun. As a result, green houses and growth rooms enable growing plants outside their natural growth season, and also growing plants of foreign climatic conditions.

Traditional light sources used for supplementing natural light (Greenhouses) or to create illumination in conditions where natural light is 100% absent (growth rooms), are High Pressure Sodium, Metal Halide and Fluorescent tubes. More recently, Light Emitting Diodes (LEDs) have evolved to a state where their light output in relation to energy input has risen and the quality of light (light spectrum) for plant growing purposes has also evolved to a level where LEDs now are usable for plant illumination.

An aspect in green house/growth room cultivation is monitoring of environmental conditions in the cultivation environment. It may be desirable to place various environmental sensors in the cultivation environment in order monitor and adjust various parameters of the cultivation environment. The environmental sensors may be used for measuring temperature, humidity, light levels, and/or CO₂, for example. If the positions of the sensors are known, the sensors can provide localized information within the cultivation environment. With higher number of sensors, a more accurate view on the localized conditions within the cultivation environment can be formed.

However, commissioning and management of the system may become increasingly difficult as the number of sensors in a cultivation system increases. Manual detection and recording of the positions of the sensors may be a cumbersome and error-prone task due to risk of human errors in manufacturing, installation and the recording of the position data.

SUMMARY OF THE INVENTION

An object of the present disclosure is to provide a method and an apparatus for implementing the method so as to alleviate the above disadvantages. The object of the disclosure is achieved by a method and an arrangement which are characterized by what is stated in the independent claims. The preferred embodiments of the disclosure are disclosed in the dependent claims.

The present disclosure describes a horticultural luminaire comprising a main light emitting unit that generates a main spectrum and at least one environmental sensor for measuring environmental data. Because LED-based light sources have a completely different technological starting point than the traditional light sources, new, additional functionalities have become available to be considered in a horticultural luminaire. A LED-based luminaire can be implemented with LED components mounted on a printed circuit board (PCB). The PCB also forms a platform also for other components than the LED component. For example, the luminaire may be provided with environmental sensor or sensors detecting for temperature, humidity, light levels, CO₂. Sensors embedded to a luminaire may even be used for monitoring plant growth and soil conditions of the plants.

As horticultural luminaires are located densely in greenhouses, and very densely in growth rooms, they are well positioned for monitoring what happens around and below them. A system with luminaires according to the present disclosure enables increasing the environmental monitoring data density significantly in greenhouses and growth rooms, as traditionally only a few sensors per greenhouse or a single sensor set have been deployed.

When a large number of luminaires continuously or frequently generated sensor data, it may be desirable to be able to accurately and easily determine the position of each luminaire so that the generated sensor data can be fully utilized. When sensor data from each luminaire can be coupled to a known location, the sensors are able to provide more detailed, localized information, and thus, more educated climate control decisions can be taken, leading to improved plant growth. Thus, horticultural luminaires according to the present disclosure may each comprise means for providing position data used to automatically determine the position of said luminaire. The ability to automatically detect the position of each luminaire (and hence the sensors within it) will greatly improve the usability of such a system and lower the threshold to its widespread adoption.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

FIG. 1 shows an exemplary diagram of a main spectrum of a main light emitting unit for efficient plant cultivation; and

FIGS. 2a to 2c show exemplary diagrams of a main spectrum, a side spectrum and their combination.

FIG. 3 shows the relationship between a horticultural lumaire and a lighting control system.

FIG. 4 shows the relationship between two horticultural lumaires and a lighting control system.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure describes a horticultural luminaire and a horticultural lighting arrangement comprising a plurality of luminaires. The present disclosure further describes a method for controlling a horticultural lighting arrangement.

In this context, a luminaire (or, interchangeably, a lighting fixture) is a device that is ready to be used as a light source, e.g. in a green house or a growth room. A luminaire comprises a frame and one or more light emitting units attached to the frame. The luminaire may further comprise at least one power unit which acts as means for converting electric energy supplied to the luminaire into a suitable form of electric energy in order to be consumed by the light emitting units. The luminaire may also comprise a cooling device, such as passive cooling in the form of cooling fins. Further, in the context of the present disclosure, a horticultural lighting arrangement comprises a plurality of horticultural luminaires, and is intended for providing lighting supporting/replacing natural light in order to cultivate crops.

The present disclosure discusses horticultural luminaires and horticultural lighting arrangements mainly in relation large-scale use. The luminaires and lighting arrangements may be intended for professional use, e.g. or research or commercial production of plants. Power rating of a horticultural luminaire according to the present disclosure may range from tens of watts to hundreds of watts, for example. Rated power consumption of a horticultural lighting arrangement may be in the range of tens of kilowatts to hundreds or thousands of kilowatts, for example. Because of high power consumption, good energy efficiency of the horticultural lighting arrangement may be desirable. Further, when a large number of luminaires are being used, maintenance of the luminaires may have logistical challenges. These aspects may not be significant (or present at all) in small-scale horticultural luminaires, such as horticultural luminaires intended for home or office use, or in small-scale horticultural lighting arrangements, such as hobbyist green houses.

A horticultural luminaire and a horticultural lighting arrangement according to the present disclosure may be used in a green house or a growth room, for example. In a greenhouse, for example, the horticultural luminaire and the horticultural lighting arrangement may be used for providing additional lighting at a desired spectrum. In a growth room, for example, the horticultural lighting arrangement may be a part of a larger climate control system that also controls temperature, humidity, and/or CO₂ concentration, for example. The lighting arrangement according to the present disclosure may be the sole source of lighting.

A horticultural luminaire according to the present disclosure comprises means for generating one or more spectrums of light. For example, the luminaire may comprise a first, main light emitting unit for generating a first, main spectrum and a first controller unit for controlling the emission intensity of the first light emitting unit.

In the context of the present disclosure, a light emitting unit may comprise one or more LEDs (Light Emitting Diodes), or one or more modules comprising a plurality of LEDs, for example. A light emitting unit may comprise one or more groups of LEDs, each group generating a different spectrum. Each LED (or group of LEDs) may generate a spectrum with one or more peaks at predetermined wavelengths. The p-n junction of a LED may be configured to emit a primary emission peaking at a certain wavelength. Further, the LED may be provided with an up-conversion material that converts (a part or all of) the primary emission into a secondary emission peaking at a second wavelength. The up-conversion materials may be phosphors, for example. The LED may be provided with a plurality of up-conversion materials resulting in peaks at a plurality of wavelengths. A light emitting unit may also be a group of LEDs (or other light source components) that together generate a predetermined spectrum.

The first controller unit may be configured to be able to adjust the emission intensity from 0.6% or 10% to 100% of the rated emission capacity (i.e. rated power) of the first light emitting unit, for example. The main spectrum may approximate the spectrum of sun light, for example. Alternatively, the main spectrum may be configured for a specific purpose. For example, the main spectrum may be configured for efficient plant cultivation in a green house or a growth room. In order to achieve this, the main spectrum may comprise peaks that coincide with absorption peaks of photoreception of plants. Two important absorption peaks of photosynthetic photoreceptors are located in the red and blue regions from 625 to 675 nm and from 425 to 475 nm, respectively. Additionally, there are also other localized peaks at near-UV (300-400 nm) and in the far-red region (700-800 nm). In addition, photomorphogenetic photoreceptors of plants have sensitivity peaks in the red at 660 nm and in the far-red at 730 nm. Green light (500-600 nm) is less efficient for photosynthesis of plants, as green plants reflect these wavelengths.

FIG. 1 shows an exemplary diagram of a main spectrum of a main light emitting unit for efficient plant cultivation. In FIG. 1, a spectrum with two distinct peaks are shown. A first, blue peak has its maximum at approximately 460 nm. The first peak may be generated with the primary emission of a LED, for example. The second, red peak has its maximum at approximately 660 nm. The second peak may be secondary emission generated with an up-conversion material from the primary emission of a LED. Because light in the range of 500-600 nm is less efficient for the photosynthesis of plants, the main spectrum may have low emissions at said range. In FIG. 1, the emission at wavelengths of 500-600 nm is below an intensity in the blue (400-500 nm) band and below an intensity in the red (600-700 nm) band.

The horticultural luminaire according to the present disclosure may further comprise means for generating at least one side spectrum that differs from the main spectrum. For example, in addition to the first light emitting unit, the luminaire may comprise a second, auxiliary light emitting unit for generating a second, side spectrum and a second controller unit for controlling the emission intensity of the auxiliary light emitting unit. The side spectrum may be independently controllable from the main spectrum. The rated emission capacity of a auxiliary light emitting unit generating a side spectrum may be only a fraction (e.g. 50% or even only 10%) of the rated emission capacity of the first light emitting unit that generates the main spectrum. In this manner, a power supply for the auxiliary light emitting unit can be implemented with smaller and less expensive components.

FIGS. 2a to 2c show exemplary diagrams of a main spectrum, a side spectrum and their combination. FIG. 2a shows an exemplary main spectrum generated by a main first light emitting unit. The main spectrum comprises a blue peak having its maximum at 450 nm and a red peak having its maximum at 660 nm. The blue and red peak coincide with absorption peaks of photosynthetic photoreception of plants. Further, the red peak coincides with an absorption peak of photomorphogenetic photoreception of plants. In addition, the main spectrum in FIG. 2a has a (low-intensity) peak having its maximum at about 540 nm. This peak coincides with a high photoreception sensitivity of a chromatic channel of insect vision. In addition, the blue peak coincides with a high photoreception sensitivity of another chromatic channel of insect vision. Thus, peaks producing emissions at two different chromatic channels of insect vision are present in FIG. 2a . Having at least some emissions at wavelengths of high sensitivity of at two different chromatic channels of insect vision can significantly improve pollination performed by insects, such as bumblebees.

FIG. 2b shows an exemplary side spectrum. The side spectrum in FIG. 2b comprises a single peak having its maximum in the far-red region at about 730 nm. This peak coincides with a second absorption peak of photomorphogenetic photoreceptors in the far-red region.

FIG. 2c shows an exemplary combination of the main and side spectrum. Photomorphogenetic responses are usually related to the sensing of the light quality in the form of the red (R) to far-red (FR) ratio (R/FR). By controlling the ratio (R/FR), photomorphogenetic responses, such as leaf expansion, neighbour perception, shade avoidance, stem elongation, seed germination and flowering induction, may be controlled.

The horticultural luminaire may also comprise means for generating a plurality of side spectrums. Each of these side spectrums may be independently controllable. The horticultural luminaire may comprise a plurality of lighting devices, and a plurality of controller units controlling the lighting devices. Each controller unit may be configured to be able to separately adjust the emission intensity of its respective lighting device between 0.6% to 100% of the rated emission capacity of said lighting device, for example.

With the side spectrum or spectrums, the main spectrum may be modified in order to achieve a desired final spectrum. With the side spectrum/spectrums, the final spectrum may be configured to represent natural lighting at a different time of year, for example. Alternatively, or in addition, the final spectrum may be configured to represent natural lighting in different environments and/or different locations around the globe.

Each luminaire according to the present disclosure may comprise control electronics configured to receive control data, and to control a final spectrum of the luminaire in response to the control data. The control electronics of each luminaire may comprise, for each light emitting unit in the luminaire, a controller unit configured to control the emission intensity of said light emitting unit on the basis of the control data. The control electronics may be implemented as an electronics card, for example. The control electronics may be implemented on the same PCB as the light emitting units of the luminaire according to the present disclosure, for example. The control data may originate from a lighting control system that controls all luminaires in a lighting arrangement, for example. In some embodiments, the control electronics may receive its control data wirelessly or via wires from a computing cloud or a central computer acting as the lighting control system.

In some embodiments, the control data received by a luminaire may represent a voltage or current reference producing a desired emission intensity of a main/side channel A controller unit in the control electronics may control a power unit acting as a power supply that drives the current flowing through the LEDs of a light emitting unit. The power unit may be a switching converter, for example. The controller unit may comprise a control loop that controls an output of the power unit towards a reference level received in the control data.

Alternatively, the control data may be used for directly controlling the power unit in order to achieve a desired emission intensity. For example, the control data may comprise information on a duty cycle of pulse width modulation (PWM) of the power unit.

In some embodiments, the power unit may be in the form of a standard power supply generating a constant voltage. The luminaire may comprise a switching circuit comprising semiconductor switches between the standard power supply and the LEDs. The control electronics may then control the modulation of the switching circuit on the basis of the control data which may represent a desired duty cycle or a desired current reference, for example.

The control data may also directly represent desired emission intensity levels. In such a case, the control electronics may comprise means for converting the intensity levels it receives into control signals controlling the power unit. These means may be in the form of a computing device and a memory, for example. The computing device may be a microprocessor, an FPGA or an ASIC, for example.

A control scheme for luminaires according to the present disclosure may take many forms. In some applications, the behaviour can be uniform for all luminaires in a growing space. All luminaires in the lighting arrangement may be provided with the same control data. However, it may also be desirable to be able to control the luminaires separately. In this manner, a space illuminated by the horticultural lighting arrangement can be divided into regions with different lighting parameters, for example in order to have different light for young plants and other light for mature plants. The emission intensities of light emitting units in a luminaire may be altered (e.g. dimmed up or down) as a group, or the emission intensities of the light emitting units may be controlled independently, thus changing the ratios between the peaks in the final spectrum of the luminaire. The generated light may also be automatically adjusted based on sensor data. For example, if ambient temperature exceeds 40° C., a horticultural luminaire according to the present disclosure may dim its emission to a 70% level as a safety function.

The control data may be provided by wired or wireless communications unit in the control electronics. For example, wired industrial field buses may be used for transmitting the data. However, when the number of luminaires in a horticultural lighting arrangement is large, providing control data to each luminaire separately with a wired connection may become impractical. Thus, the luminaires may be provided with wireless communication units. Each luminaire may comprise a wireless transceiver module, for example. The wireless module may be a UWB (Ultra Wide Band) communications, Bluetooth and Zigbee module, for example. Via the wireless communication modules, the luminaires may each receive different control data originating from a lighting control system. Each luminaire may be provided with a unique identifier, such as an identification number. With this unique identifier, each luminaire can be identified, and different control data can be directed to different luminaires.

In addition to receiving control data from the lighting control system, the control electronics of the luminaires may be configured to send information to the lighting control system. For example, the luminaire may comprise at least one sensor. The at least one sensor may be integrated to the luminaire, or it may be in the form of an attachable module. Alternatively, or in addition, the luminaire may comprise receiving means for receiving sensor data from an external sensor. Wired or wireless communication units in the luminaires may act as these receiving means. The sensors may generate various kinds of sensor data. For example, a horticultural luminaire according to the present disclosure may receive environmental sensor data on light spectrum, temperature, humidity, and/or CO₂ concentration in the vicinity of the luminaire. The luminaire may also comprise a proximity sensor that measures the distance between the luminaire and an object within a light cone of the luminaire. The plant may be plant that the luminaire is arranged to illuminate, for example. The control electronics can serve as an interface for transmitting the environmental data generated by the sensors. Sensors monitoring internal conditions (e.g. operating temperature) and external conditions (e.g. ambient environmental parameters) of luminaires may be connected to the control electronics and communicate their data via a wireless or wired communications channel to the lighting control system.

In addition to environmental sensor data, a horticultural luminaire according to the present disclosure may also provide other information to the lighting control system. For example, each luminaire may send the lighting control system information on their configuration. For example, if a modular luminaire structure is being used, the luminaire may send the lighting control system information on the type/specification of its modules. Further, the luminaires may provide information on their current operating status. Each luminaire may send the lighting control system information on its operating temperature and/or the currents flowing through its light emitting units. For example, by allocating some sensors in the luminaire to monitoring the temperature of the luminaire inside the luminaire or close to the LED components of the light emitting units, it is possible to monitor the condition of the luminaire itself. Since the use life of LEDs decays as a function of (too much) heat, it may be desirable to monitor the temperature inside and outside of the luminaire and to command the luminaire to shut down or lower light intensity (and thus decrease heat generation) as a response to excessive heat.

If the large number of luminaires in a horticultural lighting arrangement is large, commissioning of the lighting arrangement may be challenging. Manually identifying each luminaire and assigning it to a correct location within a floor plan may be prone to errors. Further, pinpointing and correcting possible errors afterwards may be difficult. Thus, it may be desirable to be able to automatically determine the locations of the luminaires. In order to be able to automatically determine their positions, the control electronics of a horticultural luminaire according to the present disclosure may be configured to determine position data. In some embodiments, each luminaire comprises an identical wireless positioning unit. During commissioning, the positioning units may communicate with each other and utilize an algorithm with which the positioning units are able to self-configure positions of the positioning units (and, thus, the luminaires). A wireless communication unit (which may also be used for receiving control data, for example) in the luminaire enables the luminaire to be positioned. Positioning of a UWB (Ultra Wide Band), Bluetooth or Zigbee module may be based on time of flight (TOF), for example. For example, a TOF of a radio signal from a wireless communications module in a luminaire to reach a separate, external receivers at known locations may be measured, and the position of the luminaire may be triangulated on the basis of the TOFs. In some embodiments, the positioning is constantly activate. However, in other embodiments, only an initial positioning during commissioning will be sufficient since the positions of the luminaires remain constant. Thus, in some embodiments, the separate, external receivers may be removed once the initial positioning has been done.

In the context of the present disclosure, the terms “location” and “position” may represent an absolute position, i.e. distance information identifying the position of the luminaire in space, e.g. in the form of coordinates. If the luminaires are arranged into an array with at even distances, position of the luminaire may be in the form as an index within the array. Further, “location” and “position” may represent a relative position, i.e. a position of a luminaire with respect to other luminaires. Relative position may be in the form of values representing distances to other luminaires, for example.

Once the positions of the luminaires in a horticultural lighting arrangement has been determined, the information may be sent to the lighting control system. Although the luminaires in the examples are arranged into a two-dimensional array in the above examples, other configurations are also possible. For example, the floor plan may dictate the positions of the luminaires. The luminaires may be arranged into an irregular configuration. Further, the luminaires may be arranged to a configuration that extends in three dimensions. For example, the luminaires may be arranged to different heights in a staggered manner.

Horticultural luminaires and a horticultural lighting arrangement according to the present disclosure enable new ways for implementing a horticultural lighting. A horticultural lighting arrangement according to the present disclosure may comprise a plurality of horticultural luminaires according to the present disclosure and a lighting control system according to the present disclosure. The lighting control system may be formed by a cloud computing system (i.e. computing cloud) or a computing device (e.g. central computer) that is connected to the luminaires. In one embodiment, the lighting control system may directly communicate with the luminaires via wired or wireless communication. In another embodiment, an auxiliary communication unit is used for arbitrating data between the lighting control system and the luminaires. The lighting control may further be connected to an external computer network, such as the Internet.

During commissioning of a horticultural lighting arrangement according to the present disclosure, a lighting control system controlling the horticultural lighting arrangement may receive configuration information originating from the luminaires. For each luminaire, this configuration information may comprise an identifier, type/specification of possible modules, and position data, for example. Based on the position data determined by the position location units of the luminaires, (absolute or relative) positions of the luminaires may be automatically determined. When the positions of the luminaires are known, the lighting control system may build a topology of the luminaires. In this context, the term “topology” represents the spatial configuration of the luminaires, i.e. how the luminaires are positioned with respect to each other in a space. When determining the topology, the lighting control system may utilize a pre-existing floor plane of the space the luminaires are commissioned in. The lighting control system may assign each luminaire to the floor plan based on the position data and the unique identifier within the within the configuration information, for example.

During use, environmental data from luminaires may be coupled to the determined positions of the luminaires, and the lighting control system may be used for storing this information. The ability to track and log environmental data with high accuracy and density improves plant breeding and crop protection development. Detailed records of the environmental conditions will enable the researchers to better identify real plant reactions to their plant-crosses or active ingredients in crop protection and not confusing environmental causes with real reactions.

The lighting control system may also provide a visual representation of the topology of the luminaires. The visual representation may be in the form of a graphical user interface shown on a display, for example. The graphical user display may show the luminaires as graphical elements. Positions of these graphical elements on the graphical user interface may correlate with the real locations of the luminaires in space. The visual representation of the topology may also show other configuration information sent by the luminaires. For example, the visual representation may show possible type/specification information on modules present in the luminaires.

The lighting control system may also utilize operating status information sent by the luminaires. The lighting control system may gather and store data on the operational data and use the gathered data for diagnostics purposes. For example, lighting control system may monitor the operating status information for deviations between the operating statuses of the luminaires. If a deviation in an operating status of a luminaire is detected (e.g. a current of a light emitting unit in a luminaire deviates significantly from currents of corresponding light emitting units of other luminaires producing the same final spectrum), the device may be considered faulty and/or scheduled for maintenance. The visual representation of the topology of the luminaires may visualize operating status information of the luminaires.

As described earlier, the luminaires may also provide the lighting control system with distance measurements generated by proximity sensors in the luminaires. Based on the distance information sent by a luminaire, an approximation of light intensity received by an object, such as plant, from the luminaire can be calculated. The distance information may also be utilized in calculating an approximation of crop yield, for example.

The lighting control system may implement various automated functions. For example, an end user may have a desired target settings for the horticultural lighting arrangement. In this context, the term “target settings” refers to pre-set settings in the form of a desired spectrum or a time-dependent sequence of spectrums, for example. The end user may send a specification describing the target settings to the light control system. Based on the received specification, the lighting control system determines appropriate control data to be sent to the luminaires. Upon receiving the control data, the luminaires control their light emitting units according to the control data. In this manner, accurate and dynamically changing light intensities can be created, light spectra or dynamic light programs spanning from seconds to years.

The lighting control system offers advantages in plant production in growing environment without natural light, such as vertical farms in warehouses, mine tunnels, basements or any other environments without natural light, where all (including light) can be fully controlled. Such production environments offer the advantage of nearly perfect control of crop production cycles, without sensitivity to outdoor light, thus being able to delivery planned crops regardless of season. This is a great advantage to the grower, as the demand for plant crops is not or seldom dependent on season. For example, a lot of strawberries are consumed in Netherlands and other European countries at Christmas, when the by nature do not grow and greenhouse production can be affected by cold and/or cloudy weather.

In order to enable easy configuration of a horticultural lighting arrangement according to the present disclosure, a collection of pre-set target settings may be generated. A cloud-based service may be used for managing the target settings, for example. A lighting control system that generates environmental sensor data can also be used for generating target settings for a climate control system. For example, once an operator has established a first successful vertical farm, it may be desirable to replicate the conditions of the first farm in the subsequent farms in new sites. Here the new system can provide both target data, based on data stored to the cloud and also measure that the targets are reach with high spatial accuracy, thanks to the dense lighting network.

In some embodiments, the lighting control system may adjust the control data in order to achieve an evenly distributed emission intensity among the luminaires. In the periphery of the arrangement of luminaires (e.g. next to walls or in the corners of a growth room), fewer luminaires are present to generate light emissions. Thus, the lighting control system may amplify the emission intensities of the luminaires in the periphery by modifying the control data sent to the luminaires.

In addition, the lighting control system may adjust the control data on the basis the distance between the luminaire and a plant illuminated by the luminaire. For example, the control system may calculate the lighting intensity received by the object on the basis of the distance and then modify the control data of the luminaire in order to achieve an even lighting intensity for all plants. Alternatively, the luminaire may receive a desired lighting intensity (and spectrum) in the control data, measure the distance between itself and the plant, and modify the emissions of its light emitting units accord according to the desired lighting intensity.

The lighting control system may also be used for research purposes. For example, the lighting control system may divide the topology of the luminaire into regions and set the luminaires to illuminate plants with different spectrums. The lighting control system may then monitor crop yield based on distance information provided by proximity sensors in the luminaires. Alternatively, or in addition, the growth of different breeds of a plant can be easily monitored with the proximity sensors.

The horticultural lighting arrangement and the lighting control system according to the present disclosure may also be used as a user interface. For example, the lighting control system may be used for defining a point/region of interest within a space illuminated by the horticultural lighting arrangement. One or more plants may be illuminated with a visibly (human vision) different lighting intensity and/or different spectrum. In this manner, one or more plants can be highlighted. Thus, locating a specific plant is easier. Further, locating luminaires that are to be maintained are easier to locate by using the same approach.

It is obvious to a person skilled in the art that the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the exampies described above but may vary within the scope of the claims. 

The invention claimed is:
 1. A horticultural luminaire comprising a main light emitting unit comprising at least one LED for generating a main spectrum of the horticultural luminaire, an environmental sensor for measuring environmental data, and control electronics configured to wirelessly determine a position of the horticultural luminaire, send out the environmental data to be received by a lighting control system, and receive control data originating from the lighting control system, and control the emission intensity of the main light emitting unit on the basis of the control data.
 2. A horticultural luminaire according to claim 1, wherein the luminaire further comprises at least one auxiliary light emitting unit comprising at least one LED for generating at least one side spectrum, and the control electronics is further configured to separately control the emission intensity of each of the at least one auxiliary light emitting unit on the basis of the control data.
 3. A horticultural luminaire according to claim 2, wherein a rated power of the at least one auxiliary light emitting unit is less than 50% of a rated power of the main light emitting unit.
 4. A horticultural luminaire according to claim 1, wherein the luminaire further comprises a proximity sensor configure to measure a distance between the luminaire and an object within a light cone of the luminaire.
 5. A horticultural lighting arrangement comprising a plurality of horticultural luminaires according to claim
 1. 6. A lighting control system for a horticultural lighting arrangement according to claim 5, wherein the lighting control system is configured to generate the control data for each of the plurality of luminaires.
 7. A horticultural lighting arrangement comprising a plurality of horticultural luminaires according to claim
 2. 8. A horticultural lighting arrangement comprising a plurality of horticultural luminaires according to claim
 3. 9. A horticultural lighting arrangement comprising a plurality of horticultural luminaires according to claim
 4. 10. A horticultural luminaire according to claim 2, wherein the luminaire further comprises a proximity sensor configure to measure a distance between the luminaire and an object within a light cone of the luminaire.
 11. A horticultural luminaire according to claim 3, wherein the luminaire further comprises a proximity sensor configure to measure a distance between the luminaire and an object within a light cone of the luminaire.
 12. A method of controlling a horticultural lighting arrangement, the method comprising: providing a lighting arrangement with a plurality of horticultural luminaires, wherein each horticultural lumaire comprises i) a main light emitting unit comprising at least one LED for generating a main spectrum of the horticultural luminaire, ii) an environmental sensor for measuring environmental data, and iii) control electronics configured to wirelessly determine a position of the horticultural luminaire, send out the environmental data to be received by a lighting control system, and receive control data originating from the lighting control system, and control the emission intensity of the main light emitting unit on the basis of the control data; using the horticultural luminaires to automatically determine positions of the luminaires; and coupling environmental data from luminaires to the determined positions of the luminaires.
 13. A method according to claim 12, wherein the method further comprises displaying representations of the environmental data on a graphical user interface on a display such that the positions of the representations of the environmental data on the graphical user interface correlate with the positions of the luminaires in the horticultural lighting arrangement.
 14. A software program product embodied in a non-transitory storage medium, having instructions that, when executed by a computing device or system, cause the computing device of system to perform the method according to claim
 12. 